Fix handling of SUSPECT connections at service termination

A peer connection in watchdog state SUSPECT is represented by a peer
table entry in diameter_service, but not by a request table entry in
diameter_peer, so diameter_service:terminate/2 could result in failures
like this:

exception error: no match of right hand side value []
  in function diameter_traffic:peer_down/1 (base/diameter_traffic.erl, line 141)
  in call from lists:foldl/3 (lists.erl, line 1263)
  in call from ets:do_foldl/4 (ets.erl, line 611)
  in call from ets:foldl/3 (ets.erl, line 600)
  in call from diameter_service:terminate/2 (base/diameter_service.erl, line 557)
  in call from gen_server:try_terminate/3 (gen_server.erl, line 648)
  in call from gen_server:terminate/10 (gen_server.erl, line 833)
  in call from gen_server:handle_msg/6 (gen_server.erl, line 679)

1 files changed, 15 insertions, 5 deletions

diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 31dd92f878..55ebcafcf9 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -554,15 +554,25 @@ terminate(Reason, #state{service_name = Name, local = {PeerT, _, _}} = S) ->
     %% wait for watchdog state changes to take care of if. That this
     %% takes place after deleting the state entry ensures that the
     %% resulting failover by request processes accomplishes nothing.
-    ets:foldl(fun(#peer{pid = TPid}, _) ->
-                      diameter_traffic:peer_down(TPid)
-              end,
-              ok,
-              PeerT),
+    ets:foldl(fun peer_down/2, ok, PeerT),
 
     shutdown == Reason  %% application shutdown
         andalso shutdown(application, S).
 
+%% peer_down/1
+%%
+%% Entries with watchdog state SUSPECT are already down: ignore the
+%% expected failure. This assumes the current implementation, but
+%% double the number of lookups (in the typical case) could be the
+%% greater evil if there are many peer connections.
+
+peer_down(#peer{pid = TPid}, _) ->
+    try
+        diameter_traffic:peer_down(TPid)
+    catch
+        error: {badmatch, []} -> ok
+    end.
+
 %% ---------------------------------------------------------------------------
 %% # code_change/3
 %% ---------------------------------------------------------------------------